| Diagram | Fig. 2 — CYLINDER AND CRANKSHAFT · ref 35 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1970 |
BSA Crankpin roller cage
Roller cage for the big-end/crankpin assembly, part number 40-0572, tied in our records to the BSA B44 engine.
This is the roller cage from a big-end assembly, the part that keeps the crankpin rollers spaced and aligned as they ride around the crankpin inside the connecting rod. It lives in the crankcase, buried under the cylinder, and shows up in the parts book under the CYLINDER AND CRANKSHAFT figure alongside the crankpin, rollers, and rod itself.
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The part number here is 40-0572, and our catalog records show it appearing across entries dated 1969-1970. The catalog listing we've cross-checked ties this cage to the B44 engine, which is a BSA, not a Triumph, so if you came here off a Triumph parts list double check you've got the right family before ordering.
A cage like this is a wear item that takes a beating over the life of a big-end - if the rollers or the cage itself get loose or worn, you'll usually hear it as knock in the bottom end. Because this is machined to work with the specific crankpin and rod bore it rides in, get us the numbers off your crank before you buy so we can confirm the fit.
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